SK Telecom unveils 688-billion-parameter AI model ahead of government evaluation

SK Telecom has unveiled A.X K2, an AI model with 688 billion parameters, ahead of the government's second evaluation round for homegrown AI foundation models. The company plans to deploy the model across industrial sites and everyday life to build a Korea-centered AI ecosystem, marking a significant scale-up from its previous release.

On Wednesday, SK Telecom said it released A.X K2 — with 688 billion parameters — on the open-source platform Hugging Face. Compared with its predecessor, A.X K1, which had 519 billion parameters, the new model offers enhanced mathematical and scientific reasoning as well as stronger Korean-language knowledge and long-context reasoning.

According to SK Telecom, A.X K2 improved average performance across 14 domestic and international benchmarks by 32.2 percentage points over A.X K1. Long-context comprehension and agent-related evaluations saw particularly sharp gains of about 83.9 percentage points.

SK Telecom attributed the performance improvements to its proprietary SGA architecture, developed in-house. The structure allows the AI to selectively reference only the most relevant information when processing long contexts, a design aimed at improving the accuracy and operational efficiency demanded in industrial settings.

The company also said A.X K2 achieved benchmark results on par with overseas AI models released within the past six months, including Qwen3.5-397B-A17B, DeepSeek-V4-Flash, GLM-5.1 and Kimi K2.6.

SK Telecom plans to expand A.X K2's reach into industrial workplaces and daily life. To that end, the model underwent four rounds of post-training to assess response quality, stability and operational efficiency. The company is also identifying use cases across manufacturing, defense and biotech.

In manufacturing, SK Telecom intends to embed practical shop-floor expertise into the AI. A representative example is the application of A.X K2 to manufacturing-specialized AI agents in partnership with steelmaker KG Steel and auto-parts manufacturer Konec. In the second half of this year, a demo version of the manufacturing AI agent is set to be deployed on the cold-rolling line at KG Steel's Dangjin factory and in Konec's casting and machining processes.

SK Telecom also worked with the Ministry of National Defense to develop three quantized models based on A.X K1. Given the defense sector's stringent security and data-sovereignty requirements, the company applied quantization technology to reduce A.X K1's memory chip usage and boost processing speed. The two organizations plan to deploy the models across Army, Navy, Air Force and Marine Corps units.

SK Telecom said it is also exploring entry into the biotech sector. The company is currently working with SK Biopharm to apply AI to the development of targeted therapies for intractable cancers. Applying SK Telecom's AI technology cut the early-stage drug development research period at SK Biopharm from the typical one to two years down to five months.

In office settings, SK Telecom integrated A.X K2 into its A.Biz service, introducing features for creating newsletters and generating reports through data collection and analysis. A lightweight version of A.X K2 is also being provided to SK Hynix for internal workplace AI tools, supporting tasks such as document drafting and information organization.

SK Telecom plans to offer its AI models via application programming interface to support the domestic AI ecosystem. Notable examples include providing A.X K1 to members of the public participating in the Ministry of Science and ICT's national AI competition and to startups selected for the Ministry of SMEs and Startups' "Challenge AX-LLM for All" program.

For everyday use, SK Telecom has applied a lightweight version of A.X K2 to its A.dot service. The "AI Suggestion" feature in A.dot Phone extracts schedules and to-do items from call content to support users' follow-up actions. A lightweight A.X K2 model also underpins part of the technology that organizes notes recorded in A.dot's "Note" feature according to their intended purpose.

SK Telecom also said it will participate in the Ministry of Science and ICT's "AI for All" initiative. The company plans to expand AI services that citizens can tangibly experience, drawing on its full-stack AI capabilities spanning models, services and infrastructure.

SK Telecom has also set plans to scale up A.X K2's successor to the trillion-parameter range. With leading global models treating trillion-scale parameters as a baseline competitive requirement, the company said it will advance the A.X model line to approach the level of major technology companies in both scale and performance.

SK Telecom said it has built a derivative lineup around A.X K2, including a vision-language model based on a vision encoder and a speech model based on audio encoder and decoder technology. The company plans to use this lineup to address diverse industrial needs.

Among the derivative models, A.X K2 VL Light-Preview and A.X K2 ALM (Audio Language Model) were developed by SK Telecom, while A.X K2 Raon-Speech is an independently developed model by Krafton.

SK Telecom highlighted A.X K2 VL Light-Preview's ability to understand images and text together, making it applicable to tasks involving reports, manuals and on-site images. The model can recognize and analyze image-format documents such as receipts and academic papers, and is capable of analyzing legal documents in image form to assess risk, as well as interpreting industrial piping diagrams.

SK Telecom is exploring the use of A.X K2 ALM — which can recognize and analyze voice from customer service calls, meetings and field environments — in call-center voice applications.

Krafton plans to apply the technology it accumulated while developing A.X K2 Raon-Speech to enhance natural voice interaction between players and AI in its future games.

"We have advanced a wide range of functions so the model can be used broadly, from individuals' daily lives to office environments and manufacturing sites," said Kim Tae-yun, head of foundation models at SK Telecom. "We will continue to apply and develop A.X K2 across diverse industries to contribute to strengthening national competitiveness."